Sign frame



FIG. 1 is a front elevational view of a sign frame showing my new design;

FIG. 2 is an isometric view thereof;

FIG. 3 is a side elevational view thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a bottom plan view thereof;

FIG. 6 is a front elevational view of a second embodiment of a sign frame;

FIG. 7 is an isometric view thereof;

FIG. 8 is a side elevational view thereof;

FIG. 9 is a top plan view thereof;

FIG. 10 is a bottom plan view thereof. 

The ornamental design for a sign frame, substantially as shown and described. 